SPI.h

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2019 ARM Limited
00003  * SPDX-License-Identifier: Apache-2.0
00004  *
00005  * Licensed under the Apache License, Version 2.0 (the "License");
00006  * you may not use this file except in compliance with the License.
00007  * You may obtain a copy of the License at
00008  *
00009  *     http://www.apache.org/licenses/LICENSE-2.0
00010  *
00011  * Unless required by applicable law or agreed to in writing, software
00012  * distributed under the License is distributed on an "AS IS" BASIS,
00013  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00014  * See the License for the specific language governing permissions and
00015  * limitations under the License.
00016  */
00017 #ifndef MBED_SPI_H
00018 #define MBED_SPI_H
00019 
00020 #include "platform/platform.h"
00021 
00022 #if DEVICE_SPI || defined(DOXYGEN_ONLY)
00023 
00024 #include "platform/PlatformMutex.h"
00025 #include "hal/spi_api.h"
00026 #include "drivers/DigitalOut.h"
00027 #include "platform/SingletonPtr.h"
00028 #include "platform/NonCopyable.h"
00029 
00030 #if defined MBED_CONF_DRIVERS_SPI_COUNT_MAX && DEVICE_SPI_COUNT > MBED_CONF_DRIVERS_SPI_COUNT_MAX
00031 #define SPI_PERIPHERALS_USED MBED_CONF_DRIVERS_SPI_COUNT_MAX
00032 #elif defined DEVICE_SPI_COUNT
00033 #define SPI_PERIPHERALS_USED DEVICE_SPI_COUNT
00034 #else
00035 /* Backwards compatibility with HALs not providing DEVICE_SPI_COUNT */
00036 #define SPI_PERIPHERALS_USED 1
00037 #endif
00038 
00039 #if DEVICE_SPI_ASYNCH
00040 #include "platform/CThunk.h"
00041 #include "hal/dma_api.h"
00042 #include "platform/CircularBuffer.h"
00043 #include "platform/Callback.h"
00044 #include "platform/Transaction.h"
00045 #endif
00046 
00047 namespace mbed {
00048 /**
00049  * \defgroup drivers_SPI SPI class
00050  * \ingroup drivers-public-api-spi
00051  * @{
00052  */
00053 
00054 struct use_gpio_ssel_t { };
00055 const use_gpio_ssel_t use_gpio_ssel;
00056 
00057 /** A SPI Master, used for communicating with SPI slave devices.
00058  *
00059  * The default format is set to 8-bits, mode 0, and a clock frequency of 1MHz.
00060  *
00061  * Most SPI devices will also require Chip Select and Reset signals. These
00062  * can be controlled using DigitalOut pins.
00063  *
00064  * @note Synchronization level: Thread safe
00065  *
00066  * Example of how to send a byte to a SPI slave and record the response:
00067  * @code
00068  * #include "mbed.h"
00069  *
00070  * SPI device(SPI_MOSI, SPI_MISO, SPI_SCLK)
00071  *
00072  * DigitalOut chip_select(SPI_CS);
00073  *
00074  * int main() {
00075  *     device.lock();
00076  *     chip_select = 0;
00077  *
00078  *     int response = device.write(0xFF);
00079  *
00080  *     chip_select = 1;
00081  *     device.unlock();
00082  * }
00083  * @endcode
00084  *
00085  * Example using hardware Chip Select line:
00086  * @code
00087  * #include "mbed.h"
00088  *
00089  * SPI device(SPI_MOSI, SPI_MISO, SPI_SCLK, SPI_CS)
00090  *
00091  * int main() {
00092  *     device.lock();
00093  *     int response = device.write(0xFF);
00094  *     device.unlock();
00095  * }
00096  * @endcode
00097  */
00098 class SPI : private NonCopyable<SPI> {
00099 
00100 public:
00101 
00102     /** Create a SPI master connected to the specified pins.
00103      *
00104      *  @note This constructor passes the SSEL pin selection to the target HAL.
00105      *  Not all targets support SSEL, so this cannot be relied on in portable code.
00106      *  Portable code should use the alternative constructor that uses GPIO
00107      *  for SSEL.
00108      *
00109      *  @note You can specify mosi or miso as NC if not used.
00110      *
00111      *  @param mosi SPI Master Out, Slave In pin.
00112      *  @param miso SPI Master In, Slave Out pin.
00113      *  @param sclk SPI Clock pin.
00114      *  @param ssel SPI Chip Select pin.
00115      */
00116     SPI(PinName mosi, PinName miso, PinName sclk, PinName ssel = NC);
00117 
00118     /** Create a SPI master connected to the specified pins.
00119      *
00120      *  @note This constructor manipulates the SSEL pin as a GPIO output
00121      *  using a DigitalOut object. This should work on any target, and permits
00122      *  the use of select() and deselect() methods to keep the pin asserted
00123      *  between transfers.
00124      *
00125      *  @note You can specify mosi or miso as NC if not used.
00126      *
00127      *  @param mosi SPI Master Out, Slave In pin.
00128      *  @param miso SPI Master In, Slave Out pin.
00129      *  @param sclk SPI Clock pin.
00130      *  @param ssel SPI Chip Select pin.
00131      */
00132     SPI(PinName mosi, PinName miso, PinName sclk, PinName ssel, use_gpio_ssel_t);
00133 
00134     /** Create a SPI master connected to the specified pins.
00135      *
00136      *  @note This constructor passes the SSEL pin selection to the target HAL.
00137      *  Not all targets support SSEL, so this cannot be relied on in portable code.
00138      *  Portable code should use the alternative constructor that uses GPIO
00139      *  for SSEL.
00140      *
00141      *  @note You can specify mosi or miso as NC if not used.
00142      *
00143      *  @param static_pinmap reference to structure which holds static pinmap.
00144      */
00145     SPI(const spi_pinmap_t &static_pinmap);
00146     SPI(const spi_pinmap_t &&) = delete; // prevent passing of temporary objects
00147 
00148     /** Create a SPI master connected to the specified pins.
00149      *
00150      *  @note This constructor manipulates the SSEL pin as a GPIO output
00151      *  using a DigitalOut object. This should work on any target, and permits
00152      *  the use of select() and deselect() methods to keep the pin asserted
00153      *  between transfers.
00154      *
00155      *  @note You can specify mosi or miso as NC if not used.
00156      *
00157      *  @param static_pinmap reference to structure which holds static pinmap.
00158      *  @param ssel SPI Chip Select pin.
00159      */
00160     SPI(const spi_pinmap_t &static_pinmap, PinName ssel);
00161     SPI(const spi_pinmap_t &&, PinName) = delete; // prevent passing of temporary objects
00162 
00163     virtual ~SPI();
00164 
00165     /** Configure the data transmission format.
00166      *
00167      *  @param bits Number of bits per SPI frame (4 - 16).
00168      *  @param mode Clock polarity and phase mode (0 - 3).
00169      *
00170      * @code
00171      * mode | POL PHA
00172      * -----+--------
00173      *   0  |  0   0
00174      *   1  |  0   1
00175      *   2  |  1   0
00176      *   3  |  1   1
00177      * @endcode
00178      */
00179     void format(int bits, int mode = 0);
00180 
00181     /** Set the SPI bus clock frequency.
00182      *
00183      *  @param hz Clock frequency in Hz (default = 1MHz).
00184      */
00185     void frequency(int hz = 1000000);
00186 
00187     /** Write to the SPI Slave and return the response.
00188      *
00189      *  @param value Data to be sent to the SPI slave.
00190      *
00191      *  @return Response from the SPI slave.
00192      */
00193     virtual int write(int value);
00194 
00195     /** Write to the SPI Slave and obtain the response.
00196      *
00197      *  The total number of bytes sent and received will be the maximum of
00198      *  tx_length and rx_length. The bytes written will be padded with the
00199      *  value 0xff.
00200      *
00201      *  @param tx_buffer Pointer to the byte-array of data to write to the device.
00202      *  @param tx_length Number of bytes to write, may be zero.
00203      *  @param rx_buffer Pointer to the byte-array of data to read from the device.
00204      *  @param rx_length Number of bytes to read, may be zero.
00205      *  @return
00206      *      The number of bytes written and read from the device. This is
00207      *      maximum of tx_length and rx_length.
00208      */
00209     virtual int write(const char *tx_buffer, int tx_length, char *rx_buffer, int rx_length);
00210 
00211     /** Acquire exclusive access to this SPI bus.
00212      */
00213     virtual void lock(void);
00214 
00215     /** Release exclusive access to this SPI bus.
00216      */
00217     virtual void unlock(void);
00218 
00219     /** Assert the Slave Select line, acquiring exclusive access to this SPI bus.
00220      *
00221      * If use_gpio_ssel was not passed to the constructor, this only acquires
00222      * exclusive access; it cannot assert the Slave Select line.
00223      */
00224     void select(void);
00225 
00226     /** Deassert the Slave Select line, releasing exclusive access to this SPI bus.
00227      */
00228     void deselect(void);
00229 
00230     /** Set default write data.
00231       * SPI requires the master to send some data during a read operation.
00232       * Different devices may require different default byte values.
00233       * For example: A SD Card requires default bytes to be 0xFF.
00234       *
00235       * @param data Default character to be transmitted during a read operation.
00236       */
00237     void set_default_write_value(char data);
00238 
00239 #if DEVICE_SPI_ASYNCH
00240 
00241     /** Start non-blocking SPI transfer using 8bit buffers.
00242      *
00243      * This function locks the deep sleep until any event has occurred.
00244      *
00245      * @param tx_buffer The TX buffer with data to be transferred. If NULL is passed,
00246      *                  the default SPI value is sent.
00247      * @param tx_length The length of TX buffer in bytes.
00248      * @param rx_buffer The RX buffer which is used for received data. If NULL is passed,
00249      *                  received data are ignored.
00250      * @param rx_length The length of RX buffer in bytes.
00251      * @param callback  The event callback function.
00252      * @param event     The event mask of events to modify. @see spi_api.h for SPI events.
00253      *
00254      * @return Operation result.
00255      * @retval 0 If the transfer has started.
00256      * @retval -1 If SPI peripheral is busy.
00257      */
00258     template<typename Type>
00259     int transfer(const Type *tx_buffer, int tx_length, Type *rx_buffer, int rx_length, const event_callback_t &callback, int event = SPI_EVENT_COMPLETE)
00260     {
00261         if (spi_active(&_peripheral->spi)) {
00262             return queue_transfer(tx_buffer, tx_length, rx_buffer, rx_length, sizeof(Type) * 8, callback, event);
00263         }
00264         start_transfer(tx_buffer, tx_length, rx_buffer, rx_length, sizeof(Type) * 8, callback, event);
00265         return 0;
00266     }
00267 
00268     /** Abort the on-going SPI transfer, and continue with transfers in the queue, if any.
00269      */
00270     void abort_transfer();
00271 
00272     /** Clear the queue of transfers.
00273      */
00274     void clear_transfer_buffer();
00275 
00276     /** Clear the queue of transfers and abort the on-going transfer.
00277      */
00278     void abort_all_transfers();
00279 
00280     /** Configure DMA usage suggestion for non-blocking transfers.
00281      *
00282      *  @param usage The usage DMA hint for peripheral.
00283      *
00284      *  @return Result of the operation.
00285      *  @retval 0 The usage was set.
00286      *  @retval -1 Usage cannot be set as there is an ongoing transaction.
00287      */
00288     int set_dma_usage(DMAUsage usage);
00289 
00290 #if !defined(DOXYGEN_ONLY)
00291 protected:
00292 
00293     /** SPI interrupt handler.
00294      */
00295     void irq_handler_asynch(void);
00296 
00297     /** Start the transfer or put it on the queue.
00298      *
00299      * @param tx_buffer The TX buffer with data to be transferred. If NULL is passed,
00300      *                  the default SPI value is sent
00301      * @param tx_length The length of TX buffer in bytes.
00302      * @param rx_buffer The RX buffer which is used for received data. If NULL is passed,
00303      *                  received data are ignored.
00304      * @param rx_length The length of RX buffer in bytes.
00305      * @param bit_width The buffers element width in bits.
00306      * @param callback  The event callback function.
00307      * @param event     The event mask of events to modify.
00308      *
00309      * @return Operation success.
00310      * @retval 0 A transfer was started or added to the queue.
00311      * @retval -1 Transfer can't be added because queue is full.
00312      */
00313     int transfer(const void *tx_buffer, int tx_length, void *rx_buffer, int rx_length, unsigned char bit_width, const event_callback_t &callback, int event);
00314 
00315     /** Put a transfer on the transfer queue.
00316      *
00317      * @param tx_buffer The TX buffer with data to be transferred. If NULL is passed,
00318      *                  the default SPI value is sent.
00319      * @param tx_length The length of TX buffer in bytes.
00320      * @param rx_buffer The RX buffer which is used for received data. If NULL is passed,
00321      *                  received data are ignored.
00322      * @param rx_length The length of RX buffer in bytes.
00323      * @param bit_width The buffers element width in bits.
00324      * @param callback  The event callback function.
00325      * @param event     The event mask of events to modify.
00326      *
00327      * @return Operation success.
00328      * @retval 0 A transfer was added to the queue.
00329      * @retval -1 Transfer can't be added because queue is full.
00330      */
00331     int queue_transfer(const void *tx_buffer, int tx_length, void *rx_buffer, int rx_length, unsigned char bit_width, const event_callback_t &callback, int event);
00332 
00333     /** Configure a callback, SPI peripheral, and initiate a new transfer.
00334      *
00335      * @param tx_buffer The TX buffer with data to be transferred. If NULL is passed,
00336      *                  the default SPI value is sent.
00337      * @param tx_length The length of TX buffer in bytes.
00338      * @param rx_buffer The RX buffer which is used for received data. If NULL is passed,
00339      *                  received data are ignored.
00340      * @param rx_length The length of RX buffer in bytes.
00341      * @param bit_width The buffers element width.
00342      * @param callback  The event callback function.
00343      * @param event     The event mask of events to modify.
00344      */
00345     void start_transfer(const void *tx_buffer, int tx_length, void *rx_buffer, int rx_length, unsigned char bit_width, const event_callback_t &callback, int event);
00346 
00347 private:
00348     /** Lock deep sleep only if it is not yet locked */
00349     void lock_deep_sleep();
00350 
00351     /** Unlock deep sleep in case it is locked */
00352     void unlock_deep_sleep();
00353 
00354 
00355 #if TRANSACTION_QUEUE_SIZE_SPI
00356     /** Start a new transaction.
00357      *
00358      *  @param data Transaction data.
00359      */
00360     void start_transaction(transaction_t *data);
00361 
00362     /** Dequeue a transaction and start the transfer if there was one pending.
00363      */
00364     void dequeue_transaction();
00365 
00366 #endif // TRANSACTION_QUEUE_SIZE_SPI
00367 #endif // !defined(DOXYGEN_ONLY)
00368 #endif // DEVICE_SPI_ASYNCH
00369 
00370 #if !defined(DOXYGEN_ONLY)
00371 protected:
00372 #ifdef DEVICE_SPI_COUNT
00373     // HAL must have defined this as a global enum
00374     typedef ::SPIName SPIName;
00375 #else
00376     // HAL may or may not have defined it - use a local definition
00377     enum SPIName { GlobalSPI };
00378 #endif
00379 
00380     // All members of spi_peripheral_s must be initialized to make the structure
00381     // constant-initialized, and hence able to be omitted by the linker,
00382     // as SingletonPtr now relies on C++ constant-initialization. (Previously it
00383     // worked through C++ zero-initialization). And all the constants should be zero
00384     // to ensure it stays in the actual zero-init part of the image if used, avoiding
00385     // an initialized-data cost.
00386     struct spi_peripheral_s {
00387         /* Internal SPI name identifying the resources. */
00388         SPIName name = SPIName(0);
00389         /* Internal SPI object handling the resources' state. */
00390         spi_t spi{};
00391         /* Used by lock and unlock for thread safety */
00392         SingletonPtr<PlatformMutex>  mutex;
00393         /* Current user of the SPI */
00394         SPI *owner = nullptr;
00395 #if DEVICE_SPI_ASYNCH && TRANSACTION_QUEUE_SIZE_SPI
00396         /* Queue of pending transfers */
00397         SingletonPtr<CircularBuffer<Transaction<SPI>, TRANSACTION_QUEUE_SIZE_SPI> > transaction_buffer;
00398 #endif
00399     };
00400 
00401     // holds spi_peripheral_s per peripheral on the device.
00402     // Drawback: it costs ram size even if the device is not used, however
00403     // application can limit the allocation via JSON.
00404     static spi_peripheral_s _peripherals[SPI_PERIPHERALS_USED];
00405     static int _peripherals_used;
00406 
00407     // Holds the reference to the associated peripheral.
00408     spi_peripheral_s *_peripheral;
00409 
00410 #if DEVICE_SPI_ASYNCH
00411     /* Interrupt */
00412     CThunk<SPI>  _irq;
00413     /* Interrupt handler callback */
00414     event_callback_t _callback;
00415     /* Current preferred DMA mode @see dma_api.h */
00416     DMAUsage _usage;
00417     /* Current sate of the sleep manager */
00418     bool _deep_sleep_locked;
00419 #endif // DEVICE_SPI_ASYNCH
00420 
00421     // Configuration.
00422     PinName _mosi;
00423     PinName _miso;
00424     PinName _sclk;
00425     PinName _hw_ssel;
00426 
00427     // The Slave Select GPIO if we're doing it ourselves.
00428     DigitalOut _sw_ssel;
00429 
00430     /* Size of the SPI frame */
00431     int _bits;
00432     /* Clock polairy and phase */
00433     int _mode;
00434     /* Clock frequency */
00435     int _hz;
00436     /* Default character used for NULL transfers */
00437     char _write_fill;
00438     /* Select count to handle re-entrant selection */
00439     int8_t _select_count;
00440     /* Static pinmap data */
00441     const spi_pinmap_t *_static_pinmap;
00442     /* SPI peripheral name */
00443     SPIName _peripheral_name;
00444     /* Pointer to spi init function */
00445     void (*_init_func)(SPI *);
00446 
00447 private:
00448     void _do_construct();
00449 
00450     /** Private acquire function without locking/unlocking.
00451      *  Implemented in order to avoid duplicate locking and boost performance.
00452      */
00453     void _acquire(void);
00454     void _set_ssel(int);
00455 
00456     /** Private lookup in the static _peripherals table.
00457      */
00458     static spi_peripheral_s *_lookup(SPIName name);
00459     /** Allocate an entry in the static _peripherals table.
00460      */
00461     static spi_peripheral_s *_alloc();
00462 
00463     static void _do_init(SPI *obj);
00464     static void _do_init_direct(SPI *obj);
00465 
00466 
00467 #endif //!defined(DOXYGEN_ONLY)
00468 };
00469 
00470 /** @}*/
00471 
00472 } // namespace mbed
00473 
00474 #endif // DEVICE_SPI || DOXYGEN_ONLY
00475 
00476 #endif // MBED_SPI_H